The present invention relates to a system for automatically opening and closing a gate valve of the type commonly used in connection with sewer systems as applied to either a residential or commercial building installations. As is well known, gate valves are traditionally installed for the purpose of preventing backflow of sewer water or other undesired fluid forced back through a pipe due to extreme back pressure. In the typical installation, such gate valves are manually operable by means of a circular wheel which is rotated by the user in order to close the valve thereby occluding the sewer pipe in situations where it is anticipated that a back pressure is being created which may possibly cause a back pressure flow of the undesired fluid.
For example, in home installations, gate valves are typically installed adjacent to the sump pumps such that when a situation arises where the sump pump can no longer handle the tremendous rise of the water level from rain water or the like, and it is evident that a back pressure situation is being created in the municipal sewer system, the gate valve may be closed thereby to occlude the sewer pipe and prevent the municipal sewer water from being forced back into the home due to the extreme water pressure being created. However, it is evident that in order to operate the gate valve, the homeowner must be present, and must manually reciprocate the gate valve in order to effect a closing off of the sewer pipe. In addition, in many instances, the homeowner may not even be alert to the fact that a back pressure situation may exist, and hence, sewer water may be backing into the system and into the home, without the homeowner having a sufficient warning in order to actually manipulate the gate valve and close the house off from the municipal system.
In order to overcome some situations relating to the lack of awareness of the homeowner, various systems have been developed in the nature of alarm systems which would alert the homeowner to a back pressure situation. Various prior patents deal with alarm systems created for such situations set for the purpose of alerting and warning the occupant of the need to close the gate valve. For example, U.S. Pat. No. 2,773,251 discloses a back flow prevention and alarm device, which in reality, is simply an alarm system for indicating leakage in a check valve or for the presence of back flow conditions. It is disclosed therein, the device depicted in the subject patent takes advantage of a pressure differential existing as between the valve chamber and the pressure in the supply line, which come under normal conditions, will not activate the contacts, but under a back flow situation, will activate the contacts to the alarm bell thereby to alert the occupant to a back flow situation, or at least the leakage of the valve. Under extreme conditions, the alarm is sounded in order to alert the operator to take such measures as may be necessary to prevent back flow from occurring.
Similarly, U.S. Pat. No. 4,398,186 is again directed to a sewer back up warning system which utilized an electrically conductive float which rises under conditions of back flow thereby to activate a rod which in turn completes an electrical circuit containing the back up alarm. It is evident that with respect to the two patents discussed herein, both disclose only an alarm system, which when activated, still requires that the operator manually close the gate valve in response to a back flow situation.
Other prior art patents have similarly attempted to devise systems for relieving the back flow pressure, such as that disclosed in U.S. Pat. No. 4,392,128. The device disclosed therein incorporates a blow-off cap including an alarm which is set off by the rising fluid immersing to contacts. As is disclosed therein, a buzzer is set off due to the rising water level, after which a blow-off cap may be exploded due to the water pressure in order to relieve the back flow pressure, although the back flow of fluid is certainly not prevented. Hence, it is still incumbent upon the oocupant to take such steps as may be necessary in order to manipulate a gate valve in order to close off the sewer pipe and stop the undesired back flow of fluid.
In terms of a system designed to actually shut off the back flow of fluid in a back flow situation, U.S. Pat. No. 4,432,388 discloses an automatic system for preventing the back up of sewage in a gravity discharge line. As disclosed therein, the device consists of an expandable bladder consisting of a folded or a pleated bladder which will expand when a reverse flow of the fluid is present. Hence, while the device disclosed therein does not operate a gate valve in order to shut off the sewer line, the device is intended for insertion into the sewer pipe line, and when a reverse flow of the fluid is realized, the bladder will expand until the opening in the sewer pipe is occluded. Legably, when the back flow situation subsides, the fluid would be expunged from the bladder such that the pleats or folds in the bladder reappear, thereby to open the fluid flow path in the proper direction.
Attempt to create an automatic system for occluding the sewer pipe is disclosed in U.S. Pat. No. 2,630,875. As shown therein, the invention consists in providing a back water valve which may be associated with a drain pipe, or the like, and may be manually operated, or automatically operated by means responsive to the rising or backing up of water in the sewer pipe or floor drain. When that does occur, the valve, upon the rise of the water, will immediately be closed and remain in such position until the liquid recedes, after which the valve will again be brought to the open position. Hence, in order for a system of the type disclosed in U.S. Pat. No. 2,630,875 to be operable, an additional valve must be positioned in the sewer line in order to operate properly.
What is significant is that the prior art has not yet been able to provide a system which may be retrofitted to an existing gate valve, and which will operate to automatically open and close the gate valve in response to a back pressure situation such as created by heavy rains, flooding or the like. The present invention is intended to provide a system which will automatically operate an existing gate valve, and which may be retrofitted to the same, such that the gate valve will be opened and closed in response to the rising and falling of the fluid in the sewer pipe, automatically, without the need of providing additional valves or the like.